Fiberglass vs. Vinyl Windows Buying Guide

When shopping for a new building or replacement windows, you choose various types of window frames. Wood windows are still available, but windows framed with aluminum, vinyl, fiberglass are in trend.

Increasingly, the choice comes down to vinyl or some modification of fiberglass or fiberglass composite. How to choose between vinyl and fiberglass? Which one is best?

Vinyl Windows

Vinyl windows are made from projected polyvinyl chloride (PVC) as the base element. They may include metal as an internal architectural element to strengthen the frames.

Vinyl windows initially appeared in the 1970s when small window fabricators started offering vinyl-framed windows to satisfy custom sizes that large window companies could not provide. It was not until the 1990s, though, that vinyl windows really became a popular option. Large companies promptly saw the value in producing vinyl windows. Today, hundreds of notable window manufacturers offer complete lines of vinyl-framed windows.

The main benefit of vinyl-framed windows is that they are affordable, costing only about half of wood-framed windows. Vinyl windows are power efficient since they are manufactured using a honeycomb structure that catches air to increase R-value. Vinyl windows can be manufactured to fit any window size.

Vinyl windows never require to be painted. This benefit can be a parallel disadvantage, though, if you want to paint your vinyl windows. Vinyl windows can be coated, but not essential, as the paint will soon peel away.

Fiberglass Windows

 Fiberglass frame windows took the widows design to the next step.

Fiberglass is created when polyester mastics are stimulated by a catalyst and then pultruded or extracted through a heated die. Beaches of glass or glass rugs are infused with resins. The finalized product is called an ancestral, and it is machinable and can be formed. Fiberglass has long been used to create ultra-strong, lightweight alloys for skis, surfboards, and boats. 

Do-It-Yourself Installation

Vinyl windows have a clear advantage, as they are comparatively easy for do-it-yourselfers to root and install by themselves. On the other hand, fiberglass windows must be placed with great precision because they are very stiff, demanding relative susceptibilities.

Professional installation is best with any new building or replacement window. But with fiberglass windows, expert installation is practically compulsory. 

Strength and Durability

Vinyl and fiberglass windows are both created from inactive substances that do not decay and are not attractive to insects like termites or woodworker ants. For that reason, vinyl and fiberglass windows stand close together for strength, especially compared to wood windows—made from natural materials that pests love to eat and which can decay.

Both windows are equally low maintenance. Rust, fungus, moss, and dirt can be hosed off, and then the frames are washed by scrubbing with a sponge and warm water.

Fiberglass gets the inclination here, mostly because the fiberglass used in the window frames consists of about 60-percent recycled glass. Vinyl windows are made from PVC synthetic, a hard material to recycle at the end of its life.


Fiberglass windows give more glass space than vinyl windows. Since vinyl is not as durable as fiberglass, more elements are needed for the frames. This means that vinyl window frames are somewhat thicker than fiberglass, affecting valuable glass space. Fiberglass windows contain more glass space than vinyl—and more glass implies more natural light.

Fiberglass can also be textured to match the texture of natural wood exactly. Fiberglass windows come in a broad range of shades not found with vinyl windows. Vinyl windows come in various baked-in colors, as do fiberglass windows. But fiberglass has the additional advantage of being paintable, while vinyl windows are challenging to paint and maintain over the long-term.

Some fiberglass windows are created with a fiberglass core and a wood surface covering the body.

Energy Efficiency

The glass fibers in fiberglass do not extend and contract under heat and cold, and thus they are a somewhat better insulator than vinyl. Fiberglass is considered roughly 15-percent higher in R-value than vinyl-framed windows. Both types, however, offer great insulating value since they are composed of hollow cavities that do an excellent job of reducing the transmission of thermal energy.

Along with better energy capability, fiberglass windows are better at giving insulation from the sound transmission.